From 9ae482104cb99076e007ae15792a3194fc1eedd8 Mon Sep 17 00:00:00 2001 From: William Breathitt Gray Date: Tue, 15 Dec 2015 18:52:44 -0500 Subject: [PATCH] gpio: 104-idi-48: Clear pending interrupt once in IRQ handler Performing a read operation on the IRQ Status register will clear the IRQ latch. Since a read operation on the IRQ Status register must be performed in the IRQ handler in order to determine if the IRQ was in fact generated by the device, the IRQ latch is consequently cleared by the IRQ handler. A spinlock is used to guarantee that each IRQ is serviced in the order it was received. Signed-off-by: William Breathitt Gray --- drivers/gpio/gpio-104-idi-48.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/drivers/gpio/gpio-104-idi-48.c b/drivers/gpio/gpio-104-idi-48.c index b5c693409a58..296dbd4cadd9 100644 --- a/drivers/gpio/gpio-104-idi-48.c +++ b/drivers/gpio/gpio-104-idi-48.c @@ -36,6 +36,7 @@ MODULE_PARM_DESC(idi_48_irq, "ACCES 104-IDI-48 interrupt line number"); * struct idi_48_gpio - GPIO device private data structure * @chip: instance of the gpio_chip * @lock: synchronization lock to prevent I/O race conditions + * @ack_lock: synchronization lock to prevent IRQ handler race conditions * @irq_mask: input bits affected by interrupts * @base: base port address of the GPIO device * @extent: extent of port address region of the GPIO device @@ -45,6 +46,7 @@ MODULE_PARM_DESC(idi_48_irq, "ACCES 104-IDI-48 interrupt line number"); struct idi_48_gpio { struct gpio_chip chip; spinlock_t lock; + spinlock_t ack_lock; unsigned char irq_mask[6]; unsigned base; unsigned extent; @@ -89,15 +91,6 @@ static int idi_48_gpio_get(struct gpio_chip *chip, unsigned offset) static void idi_48_irq_ack(struct irq_data *data) { - struct gpio_chip *chip = irq_data_get_irq_chip_data(data); - struct idi_48_gpio *const idi48gpio = to_idi48gpio(chip); - unsigned long flags; - - spin_lock_irqsave(&idi48gpio->lock, flags); - - inb(idi48gpio->base + 7); - - spin_unlock_irqrestore(&idi48gpio->lock, flags); } static void idi_48_irq_mask(struct irq_data *data) @@ -192,6 +185,8 @@ static irqreturn_t idi_48_irq_handler(int irq, void *dev_id) unsigned long gpio; struct gpio_chip *const chip = &idi48gpio->chip; + spin_lock(&idi48gpio->ack_lock); + spin_lock(&idi48gpio->lock); cos_status = inb(idi48gpio->base + 7); @@ -199,8 +194,10 @@ static irqreturn_t idi_48_irq_handler(int irq, void *dev_id) spin_unlock(&idi48gpio->lock); /* IRQ Status (bit 6) is active low (0 = IRQ generated by device) */ - if (cos_status & BIT(6)) + if (cos_status & BIT(6)) { + spin_unlock(&idi48gpio->ack_lock); return IRQ_NONE; + } /* Bit 0-5 indicate which Change-Of-State boundary triggered the IRQ */ cos_status &= 0x3F; @@ -216,6 +213,8 @@ static irqreturn_t idi_48_irq_handler(int irq, void *dev_id) } } + spin_unlock(&idi48gpio->ack_lock); + return IRQ_HANDLED; } -- 2.39.5